Schaaf Christian, Gekle Stephan
Biofluid Simulation and Modeling, Department of Physics, University of Bayreuth, 95440 Bayreuth, Germany.
Phys Rev E Stat Nonlin Soft Matter Phys. 2015 Sep;92(3):032718. doi: 10.1103/PhysRevE.92.032718. Epub 2015 Sep 18.
We calculate the local dielectric function ɛ(r) inside the hydration layer around a spherical solute (i) from molecular dynamics simulations including explicit solutes and (ii) theoretically using the nonlocal dielectric function of bulk water which includes the radial electric field, but not the explicit solute. The observed agreement between the two concepts shows that while ɛ(r) is strongly different from bulk, this difference is not due to restructuring of the hydrogen bond network but is mostly a consequence of the field geometry. The dielectric response differs for anions and cations, yielding a natural explanation for the well-known charge asymmetry of ionic solvation in agreement with experimental data.
我们通过以下两种方式计算球形溶质（i）周围水化层内的局部介电函数ɛ(r)：一是进行包含明确溶质的分子动力学模拟；二是从理论上使用包含径向电场但不包含明确溶质的体相水的非局部介电函数。这两种方法所得结果的一致性表明，虽然ɛ(r)与体相有很大差异，但这种差异并非源于氢键网络的重构，而主要是场几何结构的结果。阴离子和阳离子的介电响应不同，这与实验数据一致，为离子溶剂化中众所周知的电荷不对称现象提供了自然的解释。
